According to a City of Irvine document, 400 Spectrum Center tower will become the twin to the existing 200 Spectrum Center tower. The upcoming second tower is also from the Irvine Company and will stand at 20 stories tall.

Here is additional detail from a previous LAOCDB report: "...According to the documentsattached to the agenda, the office tower will have the same type of design as its under construction neighbor, _200 Spectrum Center. The proposed office tower has a proposed height of 323 feet and 4 inches. The 200 Spectrum Center tower is also 323 ft tall and is currently the titleholder of tallest building in Orange County. The 400 Spectrum Center project also would entail providing 1,313 parking spaces."

From observation, it appears the 400 Spectrum Center is undergoing site prep as there is a heavy presence of construction equipment and the entire site is fenced off. Additionally, some of the parking pavement has been dug out. ​​